Learn Ruby-on-rails - 10 Code Examples & CST Typing Practice Test

Ruby on Rails (Rails) is a full-stack, server-side web application framework written in Ruby. It emphasizes convention over configuration, DRY (Don't Repeat Yourself) principles, and rapid development.

View all 10 Ruby-on-rails code examples →

Rails Simple Counter App Rails Hello World API Rails Query Parameter Example Rails JSON Response Example Rails POST Form Example Rails Path Parameter Example Rails Error Handling Example Rails Redirect Example Rails Multiple Routes Example Rails Service Object Example

Learn RUBY-ON-RAILS with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Rails Simple Counter App

# config/routes.rb
Rails.application.routes.draw do
    get '/counter', to: 'counter#show'
    post '/counter/increment', to: 'counter#increment'
    post '/counter/decrement', to: 'counter#decrement'
    post '/counter/reset', to: 'counter#reset'
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    @@count = 0

    def show
        render html: "<h2>Counter: #{@@count}</h2>".html_safe
    end

    def increment
        @@count += 1
        redirect_to '/counter'
    end

    def decrement
        @@count -= 1
        redirect_to '/counter'
    end

    def reset
        @@count = 0
        redirect_to '/counter'
    end
end

Demonstrates a simple Rails controller and view for a counter using in-memory state (for demonstration purposes).

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Rails Hello World API

# config/routes.rb
Rails.application.routes.draw do
    get '/hello', to: 'hello#index'
end

# app/controllers/hello_controller.rb
class HelloController < ApplicationController
    def index
        render json: { message: 'Hello, Rails!' }
    end
end

A minimal Rails API controller returning Hello World.

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Rails Query Parameter Example

# config/routes.rb
Rails.application.routes.draw do
    get '/greet', to: 'greet#index'
end

# app/controllers/greet_controller.rb
class GreetController < ApplicationController
    def index
        name = params[:name] || 'Guest'
        render json: { message: "Hello, #{name}" }
    end
end

Demonstrates using query parameters in Rails controller.

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Rails JSON Response Example

# config/routes.rb
Rails.application.routes.draw do
    get '/json', to: 'json#index'
end

# app/controllers/json_controller.rb
class JsonController < ApplicationController
    def index
        render json: { message: 'Hello, Rails JSON' }
    end
end

Return JSON response from Rails controller.

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Rails POST Form Example

# config/routes.rb
Rails.application.routes.draw do
    post '/form', to: 'form#submit'
end

# app/controllers/form_controller.rb
class FormController < ApplicationController
    def submit
        name = params[:name]
        render json: { message: "Hello, #{name}" }
    end
end

Handle POST requests with form parameters in Rails.

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Rails Path Parameter Example

# config/routes.rb
Rails.application.routes.draw do
    get '/user/:id', to: 'user#show'
end

# app/controllers/user_controller.rb
class UserController < ApplicationController
    def show
        id = params[:id]
        render json: { user_id: id }
    end
end

Use path parameters in Rails routes.

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Rails Error Handling Example

# config/routes.rb
Rails.application.routes.draw do
    get '/error', to: 'error#index'
end

# app/controllers/error_controller.rb
class ErrorController < ApplicationController
    def index
        raise 'This is an error'
    rescue => e
        render json: { error: e.message }, status: 400
    end
end

Demonstrates basic exception handling in Rails controller.

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Rails Redirect Example

# config/routes.rb
Rails.application.routes.draw do
    get '/redirect', to: 'redirect#index'
    get '/counter', to: 'counter#show'
end

# app/controllers/redirect_controller.rb
class RedirectController < ApplicationController
    def index
        redirect_to '/counter'
    end
end

Redirect request to another route in Rails controller.

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Rails Multiple Routes Example

# config/routes.rb
Rails.application.routes.draw do
    get '/', to: 'home#index'
    get '/about', to: 'home#about'
end

# app/controllers/home_controller.rb
class HomeController < ApplicationController
    def index
        render plain: 'Home'
    end

    def about
        render plain: 'About'
    end
end

Handle multiple routes in a single Rails application.

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Rails Service Object Example

# app/services/counter_service.rb
class CounterService
    @@count = 0
    def self.get_count
        @@count
    end
    def self.increment
        @@count += 1
    end
    def self.reset
        @@count = 0
    end
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    def show
        render json: { count: CounterService.get_count }
    end
    def increment
        CounterService.increment
        redirect_to '/counter'
    end
    def reset
        CounterService.reset
        redirect_to '/counter'
    end
end

Use a service object to manage counter state.

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Frequently Asked Questions about Ruby-on-rails

What is Ruby-on-rails?

What are the primary use cases for Ruby-on-rails?

Building full-stack web applications. Developing RESTful APIs. Rapid MVP and startup projects. Database-driven enterprise apps. E-commerce platforms and SaaS products

What are the strengths of Ruby-on-rails?

Rapid development with sensible defaults. Large ecosystem of gems (libraries). Strong community and documentation. Built-in security features. Integrated testing support

What are the limitations of Ruby-on-rails?

Performance may lag behind lighter frameworks. Monolithic by default, less flexible for microservices. Learning curve for Rails conventions. Can be overkill for very small apps. Upgrading major versions can require significant refactoring

How can I practice Ruby-on-rails typing speed?

CodeSpeedTest offers 10+ real Ruby-on-rails code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Code Sample Descriptions

Rails Simple Counter App

# config/routes.rb
Rails.application.routes.draw do
    get '/counter', to: 'counter#show'
    post '/counter/increment', to: 'counter#increment'
    post '/counter/decrement', to: 'counter#decrement'
    post '/counter/reset', to: 'counter#reset'
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    @@count = 0

    def show
        render html: "<h2>Counter: #{@@count}</h2>".html_safe
    end

    def increment
        @@count += 1
        redirect_to '/counter'
    end

    def decrement
        @@count -= 1
        redirect_to '/counter'
    end

    def reset
        @@count = 0
        redirect_to '/counter'
    end
end

Demonstrates a simple Rails controller and view for a counter using in-memory state (for demonstration purposes).

Let’s Try →

Rails Hello World API

# config/routes.rb
Rails.application.routes.draw do
    get '/hello', to: 'hello#index'
end

# app/controllers/hello_controller.rb
class HelloController < ApplicationController
    def index
        render json: { message: 'Hello, Rails!' }
    end
end

A minimal Rails API controller returning Hello World.

Let’s Try →

Rails Query Parameter Example

# config/routes.rb
Rails.application.routes.draw do
    get '/greet', to: 'greet#index'
end

# app/controllers/greet_controller.rb
class GreetController < ApplicationController
    def index
        name = params[:name] || 'Guest'
        render json: { message: "Hello, #{name}" }
    end
end

Demonstrates using query parameters in Rails controller.

Let’s Try →

Rails JSON Response Example

# config/routes.rb
Rails.application.routes.draw do
    get '/json', to: 'json#index'
end

# app/controllers/json_controller.rb
class JsonController < ApplicationController
    def index
        render json: { message: 'Hello, Rails JSON' }
    end
end

Return JSON response from Rails controller.

Let’s Try →

Rails POST Form Example

# config/routes.rb
Rails.application.routes.draw do
    post '/form', to: 'form#submit'
end

# app/controllers/form_controller.rb
class FormController < ApplicationController
    def submit
        name = params[:name]
        render json: { message: "Hello, #{name}" }
    end
end

Handle POST requests with form parameters in Rails.

Let’s Try →

Rails Path Parameter Example

# config/routes.rb
Rails.application.routes.draw do
    get '/user/:id', to: 'user#show'
end

# app/controllers/user_controller.rb
class UserController < ApplicationController
    def show
        id = params[:id]
        render json: { user_id: id }
    end
end

Use path parameters in Rails routes.

Let’s Try →

Rails Error Handling Example

# config/routes.rb
Rails.application.routes.draw do
    get '/error', to: 'error#index'
end

# app/controllers/error_controller.rb
class ErrorController < ApplicationController
    def index
        raise 'This is an error'
    rescue => e
        render json: { error: e.message }, status: 400
    end
end

Demonstrates basic exception handling in Rails controller.

Let’s Try →

Rails Redirect Example

# config/routes.rb
Rails.application.routes.draw do
    get '/redirect', to: 'redirect#index'
    get '/counter', to: 'counter#show'
end

# app/controllers/redirect_controller.rb
class RedirectController < ApplicationController
    def index
        redirect_to '/counter'
    end
end

Redirect request to another route in Rails controller.

Let’s Try →

Rails Multiple Routes Example

# config/routes.rb
Rails.application.routes.draw do
    get '/', to: 'home#index'
    get '/about', to: 'home#about'
end

# app/controllers/home_controller.rb
class HomeController < ApplicationController
    def index
        render plain: 'Home'
    end

    def about
        render plain: 'About'
    end
end

Handle multiple routes in a single Rails application.

Let’s Try →

Rails Service Object Example

# app/services/counter_service.rb
class CounterService
    @@count = 0
    def self.get_count
        @@count
    end
    def self.increment
        @@count += 1
    end
    def self.reset
        @@count = 0
    end
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    def show
        render json: { count: CounterService.get_count }
    end
    def increment
        CounterService.increment
        redirect_to '/counter'
    end
    def reset
        CounterService.reset
        redirect_to '/counter'
    end
end

Use a service object to manage counter state.

Let’s Try →

Frequently Asked Questions about Ruby-on-rails

What is Ruby-on-rails?

What are the primary use cases for Ruby-on-rails?

Building full-stack web applications. Developing RESTful APIs. Rapid MVP and startup projects. Database-driven enterprise apps. E-commerce platforms and SaaS products

What are the strengths of Ruby-on-rails?

Rapid development with sensible defaults. Large ecosystem of gems (libraries). Strong community and documentation. Built-in security features. Integrated testing support

What are the limitations of Ruby-on-rails?

How can I practice Ruby-on-rails typing speed?

CodeSpeedTest offers 10+ real Ruby-on-rails code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.